The invention relates to an apparatus and method for facilitating continuous operation of fabric treating equipment.
Fabric treating equipment, e.g., dipping units, often contain complex arrangements of drive and idle rolls, ovens and wind-up, that are used to guide the fabric through the dip unit for adhesive application, drying, heat treating and tensioning operations. The initial threading of a fabric through this complex arrangement is a difficult process, and a time-consuming process, usually in excess of six hours.
Once a fabric has been guided through the equipment, however, continuous operation can be maintained by tying the leading end of a new roll of fabric to the trailing end of a depleted roll of fabric before the end of the depleted roll enters the fabric treating equipment.
Sewing one roll of fabric to the next roll, before the let-off or accumulator, is the fastest means conventionally used to run a dip unit continuously. For continuous operation, it is important that these sewn splices can be made quickly, and do not fail while being processed under tension.
In recent years, nylon monofilament has become an accepted reinforcement material in tires and other composites. Nylon monofilament fabric, especially fabric comprising monofilaments held together with low strength pick (i.e. fill or weft) cords, cannot be sewn to a liner or to another monofilament fabric at the treatment unit. The needles on the sewing machine tend to break when striking the solid nylon monofilaments, thus shutting down the fabric treatment.
A new manufacturing method, and new apparatus are needed that will make possible economical processing of monofilament reinforcing material.
After evaluating numerous methods of attaching one roll of fabric to another, the present inventors decided to try welding, especially ultrasonic welding.
Ultrasonic welding uses the generation of high frequency (e.g. 20 kHz or 40 kHz) mechanical vibrations which are transmitted to a welding horn. This horn applies a force at the surface of the materials to be bonded, and uses intermolecular friction at the interface, caused by the ultrasonic excitation, to melt the material. The force is maintained after the vibration is stopped, and upon cooling a weld is produced.
French patent No. 2,193,388 discloses a process and apparatus for connecting the posterior end of a first band of material to the anterior end of a new band of material on processing equipment. One of the methods described for connecting the two ends together comprises, when the material is a type that can be welded, welding the two ends together.
EP0015871 discloses a method for attaching two pieces of cloth together which comprises the use of ultrasonic welding. Since the use of relatively light weight cloths are the main object of the patent, special techniques wherein a sheet of paper is disposed between the anvil and cloths, and possibly between the cloths and the welding head are described. The paper provides a mechanical barrier and a heat insulative barrier that makes the process suitable for light weight material.
It is an object of the invention to use welding techniques to make economical the processing of monofilament reinforcement for use in composites.
Other objects of the invention will be apparent from the following description and claims.
A method of continuous operation of a fabric-handling unit for processing a fabric (34) made from thermoset cords or monofilaments comprises the steps of (a) feeding a leading end of a first roll of fabric (34) into a handling unit through the mechanisms of the handling unit, (b) processing the first roll of fabric (34) to a trailing end of the first roll, (c) welding a leading end of a second roll of fabric to the trailing end of the first roll of fabric (34), and (d) continuing the operation of the handling unit by processing the second roll of fabric (34).
Also provided is a method of continuous operation of a fabric-handling unit for processing a fabric (34) made from thermoset cords or monofilaments comprising the steps of (a) feeding a leading end of a first roll of fabric (34) into a handling unit through various nips and rolls of the handling unit, (b) processing the first roll of fabric (34) to a trailing end of the first roll, (c) welding a first fabric tabby (38) comprising thermoset material to the trailing end of the first roll of fabric (34), (d) welding a second fabric tabby (38) comprising thermoset material to a leading end of a second roll of fabric (34), (e) connecting the first tabby (38) to the second tabby (38), and (f) continuing the operation of the handling unit by processing the second roll of fabric (34).
The method of the invention is useful for making a roll of fabric (34) using 6 to 40 e.p.i. (2.4 to 15.7 e.p.c.) of 2,000 to 20,000 dTex thermoset monofilaments (33) in the warp direction, and 1 to 8 e.p.i. (2.4 to 3.1 e.p.c.) pick cords (35) in the weft direction. A tabby (38) made from square woven thermoset cords having a linear density of 660 to 10,000 dTex can be used to tie rolls of fabric together.
The method is conveniently carried out by welding the tabby (38) to the fabric (34) at a weaving loom using at least one row of weld points (40).
The method can be carried out by mounting a welding apparatus (14) on a rail (16) that is attached to a cart (26) so that it is movable relative to fabric which is being welded, and providing a welding apparatus (14) having a single anvil (22) having a flat surface and a length sufficient to weld a full width of fabric (34) without changing a position of the fabric (34) or the anvil (12).
In the illustrated embodiment, the method is carried out by placing the tabby (38) between the fabric and a welding head (22) on a welding apparatus (14).
Also provided is an apparatus for welding comprising a flat anvil (12) which is at least two inches (5.08 cm) wide and at least eighteen inches (45.7 cm) long, and a welding apparatus (14). In the illustrated embodiment, the anvil (12) is mounted on a frame (18) and a rail (16) is mounted on frame (18) parallel to anvil (12), and welding apparatus (14) is mounted on rail (16) and is movable on rail (16), and the frame (18) is on a cart (26).
The apparatus (10) including the welding apparatus (14), frame (18) and anvil (12) is mobile.
The welding head (22) is rotatable to provide welds at any angle, and can be raised or lowered.
The apparatus frame (18) has a support bar (24) which is movable to open an end of frame (18), and frame (18) is adapted to surround the fabric from a loom, and cart (26) is adapted to be placed between a loom and a windup stand adapted for rolling fabric onto a spool.
In one embodiment, the apparatus has a light curtain, i.e. light sensors, which surrounds critical portions of the apparatus, and when a light beam to one of the sensors is broken the apparatus shuts down.
The apparatus may also have sensors associated with welding head (22) which provide information to an electronic interface (15) wherein the sensor data is used to modify program parameters for weld head (22) concerning pressure against a sample, residence time for welding, and cool down time.